A fibre-optic transceiver module typically comprises an output stage circuit for an interface between the transceiver module and a circuit board for receiving the transceiver module. The output stage circuit is usually manufactured as part of an integrated circuit for connection to the circuit board, the integrated circuit often being capable of generating a number of output signals respectively at different output terminals or pads. The output signals generated have respective different logic levels associated therewith, each confirming to known logic families, for example, PECL, CML and/or TTL.
A disadvantage of providing different output signals at respectively different output terminals is that selection of one of the number of output signals requires a switch external to the integrated circuit to switch a desired output signal onto the circuit board, or hardwiring of an output terminal, corresponding to the desired logic family, to the circuit board. Unfortunately, the need for the external switch is accompanied by component costs, board space penalties and research and development set-up time costs. The option of hardwiring the integrated circuit is at the cost of a reducing in flexibility.
Another known solution is to design the circuit board to accommodate two similarly configured integrated circuits in a same location on the circuit board. During manufacture of the transceiver module, one of the two integrated circuits is simply selected, depending upon the output stage required. However, the topology of the output stage cannot be changed easily without remanufacture, constituting a flexibility penalty.